A security researcher asked a federal judge Wednesday to let a challenge to the Digital Millennium Copyright Act continue.

Attorneys for Ben Edelman, who specializes in investigating flaws in blocking software, filed a 26-page document arguing that his work is imperiled by legal threats from N2H2, a filtering company based in Seattle.

N2H2 has asked a Massachusetts judge to dismiss the case, which the American Civil Liberties Union brought in July to let Edelman create and distribute a utility that decrypts N2H2's secret list of forbidden Web sites. The ACLU wants a court to declare that Edelman's research is not barred by the DMCA, by N2H2's shrinkwrap license, trade secret laws or other copyright laws.

"We're confident that the court will deny the defendants' motion to dismiss since they clearly intend to pursue their legal rights against Edelman if he goes forward with his research," said Ann Beeson, an ACLU staff attorney.

By suing on behalf of Edelman, who is a researcher at Harvard Law School's Berkman Center and a first-year law student there, the civil liberties group hopes to prompt the first ruling that would curtail the DMCA's wide reach.

After the DMCA was used to pressure Princeton professor Ed Felten and his colleagues into abandoning a presentation last year, the law became an instant magnet for criticism. But so far, every judge has upheld the DMCA's broad restrictions on the "circumvention of copyright protection systems."

N2H2 has dismissed Edelman's concerns as "hypothetical," but the company also said in a recent filing with the Securities and Exchange Commission that it intends "to assert all of our legal rights against Edelman if he engages in future activity that violates the agreement of our proprietary rights."

An N2H2 spokesman said he would have to read the ACLU's filing before he could comment on it.

The ACLU is suing under a federal law called the Declaratory Judgment Act, which permits a judge to rule on the rights of "any interested party seeking such declaration" when there is an actual controversy taking place.

N2H2 says that because it has not directly threatened to sue Edelman and because the Harvard student has not actually gone ahead and investigated N2H2's products, there is no current legal controversy. U.S. District Judge Garrett Brown ruled last November that Felten had no realistic threat of being sued and dismissed the case.

"N2H2 has repeatedly demonstrated its intent to use all available legal remedies to prevent the public--and Edelman specifically--from obtaining access to its block list," the ACLU's brief says. "Were Edelman to engage in his constitutionally protected research, N2H2 would undoubtedly sue him."

Last week, Google admitted, in response to Edelman's work, that it has quietly deleted more than 100 controversial sites from some search result listings. Edelman also testified as an expert witness in another ACLU case challenging a library filtering law.

A controversial law
The ACLU's lawsuit seeks permission for Edelman to do three things: decrypt N2H2's blacklist, publish the decrypted blacklist, and distribute the decoding utility.

In October 2000, the Library of Congress said the DMCA's general prohibition on "circumvention" of technology did not apply to research that decoded "lists of Web sites blocked by filtering software applications." But it does not permit a researcher to distribute a decryption utility.

Because the DMCA has been used to threaten security researchers, it has become wildly unpopular among technologists and academics. In July, Hewlett-Packard used the DMCA in a letter threatening a team of researchers who publicized a vulnerability in the company's Tru64 Unix operating system.

Earlier this month, Reps. Rick Boucher, D-Va., and John Doolittle, R-Calif., introduced a bill called the Digital Media Consumers' Rights Act that would amend the DMCA and offer more protection to researchers.